bbowen@megatest.UUCP (Bruce Bowen) (06/28/90)
I have a 386 with a VGA monitor with which I can display, using cshow, 256 color gif files with fairly accurate color reproduction. I have Turbo C professional, which comes with their "BGI" graphics library. Looking thru the library documentation (and running some experiments) it appears that, with their bgi VGA driver, I can only have 16 colors on the screen at any one time, although I am able to change the color pallette and access a broad range of colors. Is this a limitation of the VGA standard? If so, how do programs like "cshow" work, that accuratly display a much greater that 16 color image on the monitor? -Bruce megatest!bbowen@sun.UUCP
gordon@osiris.cso.uiuc.edu (John Gordon) (06/29/90)
The 16-color limit is the fault of Borland's VGA driver. (Although
maybe supporting minimum VGA was the only way for them to do it...)
---
John Gordon
Internet: gordon@osiris.cso.uiuc.edu #include <disclaimer.h>
gordon@cerl.cecer.army.mil #include <clever_saying.h>
GEnie: j.gordon14 phil@pepsi.amd.com (Phil Ngai) (06/30/90)
In article <13360@megatest.UUCP> bbowen@megatest.UUCP (Bruce Bowen) writes: | |it appears that, with their bgi VGA driver, I can only have 16 colors on |the screen at any one time, although I am able to change the color |pallette and access a broad range of colors. Is this a limitation of |the VGA standard? If so, how do programs like "cshow" work, that |accuratly display a much greater than 16 color image on the monitor? The IBM VGA can only display 16 colors in its highest resolution mode (640x480). You have to go down to 320x200 to get 256 colors. The cloners provided extended resolution modes, and they all did it in a different way. 640x480x256 is a non-standard mode. CSHOW does it by having drivers for each different board. I assume that Borland did not provide support for 320x200x256 mode, or the structure to allow drivers for extended VGA modes. -- Phil Ngai, phil@amd.com {uunet,decwrl,ucbvax}!amdcad!phil PALASM 90: it's not the same old PALASM any more!
torkil@psivax.UUCP (Torkil Hammer) (07/06/90)
In article <1990Jun29.194631.29214@amd.com> phil@pepsi.amd.com (Phil Ngai) writes:
# mode (640x480). You have to go down to 320x200 to get 256 colors.
# The cloners provided extended resolution modes, and they all did
# it in a different way. 640x480x256 is a non-standard mode. CSHOW
# does it by having drivers for each different board. I assume that
# Borland did not provide support for 320x200x256 mode, or the
# structure to allow drivers for extended VGA modes.
The standard BGI drivers support up to VGA mode 12 (16 colors).
So it is correct that Borland did not provide support for 256 colors.
However, you can get a VGA mode 13 (320x200x256) BGI driver from SIMTEL.
I have used it with TC 2.0 and an ATI Wonder card, and it works.
There may be subtle differences between the way various VGA cards must
be programmed to use the 256 colors. At least, the ATI card is quirky.
Also, the TC 2.0 supports super VGA modes as long as you have the BGI driver.
This will depend on mode and card. I have used 800x600x256 and
1024x768x16 on the 512 kb ATI/multisync monitor combination, and while
some modes are slow, they work.
So, while the mode 13 driver should work (with allowance for quirks)
on all VGA cards, the SVGA drivers are not interchangable.
BTW, the way of using user supplied BGI drivers is illogical, but it
is documented in bits and pieces. One would think that you install the
driver and select mode later, but you install the driver in the desired
mode and if you want to change mode later you must re-install. It does not
take text string pointers, either. You must use the text string
directly in the install function.
Torkil Hammerwoody@eos.UUCP (Wayne Wood) (07/10/90)
In article <3439@psivax.UUCP> torkil@psivax.UUCP (Torkil Hammer) writes: >In article <1990Jun29.194631.29214@amd.com> phil@pepsi.amd.com (Phil Ngai) writes: >Also, the TC 2.0 supports super VGA modes as long as you have the BGI driver. >This will depend on mode and card. I have used 800x600x256 and >1024x768x16 on the 512 kb ATI/multisync monitor combination, and while >some modes are slow, they work. =I got the ATI drivers from Borland. I am also a registered owner of =TC 2.0 professional, and I wrote a very nice letter, and I included =a floppy and a SASE. =I had no problems getting them, it just took some weeks. =Anyway, they work with all ATI SVGA graphics modes, not all that =great I would say, but they work. I don't know what the difference =between a 'new' and an 'old' version would be. =BTW, don't bother asking me for copies. I can not send them from this =workstation, and my 386 is not online. okay... how did you manage to get these drivers when BORLAND repeatedly insists they don't have them? we are running a 512kb ATI/Multisync combination and we haven't gotten any of the SVGA/ATI modes to run. care to elaborate?? /*** woody **************************************************************** *** ...tongue tied and twisted, just an earth bound misfit, I... *** *** -- David Gilmour, Pink Floyd *** ****** woody@eos.arc.nasa.gov *** my opinions, like my mind, are my own ******/
semicon@watsci.waterloo.edu (Robert Adsett) (07/10/90)
In article <13360@megatest.UUCP> bbowen@megatest.UUCP (Bruce Bowen) writes: > > I have a 386 with a VGA monitor with which I can display, using cshow, >256 color gif files with fairly accurate color reproduction. I have >Turbo C professional, which comes with their "BGI" graphics library. >Looking thru the library documentation (and running some experiments) >it appears that, with their bgi VGA driver, I can only have 16 colors on >the screen at any one time, although I am able to change the color >pallette and access a broad range of colors. Is this a limitation of >the VGA standard? If so, how do programs like "cshow" work, that >accuratly display a much greater that 16 color image on the monitor? It's true that the drivers shipped with TC only support up to 16 simultaneous colours. Borland does ship a 320x200x256 colour VGA driver with their BGI development kit (available on SIMTEL20 among others). I have also just downloaded a library that allows you to write BGI drivers in C to the listserver that is associated with the TURBOC-L list. It includes 4 drivers complete with source code plus one other one that I've picked up. The drivers currently included support 1) ATI VGA Wonder 256 colour modes 2) Number Nine's Revolution 1024x8 3) Data Translations DT2851 4) A rather peculiar Tecmar Graphics Master Configuration 5) A range of 16 colour SVGA modes To get the file send mail to listserv@ucf1vm.bitnet containing the line get cbgi110 xxe turboc-l To subscribe to the list send mail to listserv@ucf1vm.bitnet containing the line sub turboc-l your name To get help send mail to listserv@ucf1vm.bitnet containing the line help -- Robert Adsett <semicon@watsci.UWaterloo.ca> Dept. of Phys, Univ. of Waterloo, Waterloo Ont. Canada
L.Parkes@comp.vuw.ac.nz (Lloyd Parkes) (07/10/90)
In article <6901@eos.UUCP> woody@eos.UUCP (Wayne Wood) writes: In article <3439@psivax.UUCP> torkil@psivax.UUCP (Torkil Hammer) writes: >In article <1990Jun29.194631.29214@amd.com> phil@pepsi.amd.com (Phil Ngai) writes: okay... how did you manage to get these drivers when BORLAND repeatedly insists they don't have them? we are running a 512kb ATI/Multisync combination and we haven't gotten any of the SVGA/ATI modes to run. It would help if you said which VGA board you had. ATI sell 2 (3?) different types of VGA card. There is no reason why their SVGA modes should be even remotely compatible. Lloyd -- ------------------------------------------------------------------------ Lloyd Parkes | Bix Licks Stick's Tricks lloyd@comp.vuw.ac.nz | Bix Barton Master of the Rum and Uncanny ------------------------------------------------------------------------